The Analysis of Thermal Power Stations and their Interaction with the Power System using Simulator Test Methods

Doktorsavhandling, 1996

This thesis describes a new method of testing power stations with regard to their frequency control behaviour and analyses results obtained using this new method. The test concept is based on that the power station unit to be tested remains synchronized onto its normal strong network, whereas the frequency control behaviour is set up to be that of the conditions if the unit was working on a much smaller network, using a computer based simulator system and feeding simulated control signals to the input of the units frequency control system. For preliminary tests or for testing conditions that could be hazardous to test on a real unit, the system can also be connected to a power station simulator simulating the unit, where such a simulator is available. The method has been tested extensively, first on a power station simulator and then in field tests against three different real power station units at the Stenungsund power station, Stenungsund, Sweden. Based on these tests models are developed for the turbine systems, the steam systems, the frequency control systems and other vital systems of a thermal power plant. It analyses how the expected response of this type of a unit would be under different conditions,e.g. island operation and gives tools and recommendations for testing of such power plants with this method. A certain analysis is also done with regard to the ability of a thermal power station of the type tested to be responsible for the frequency control of a small island network, if such operation should become necessary. It concludes that these possibilities are perhaps better then what would be generally expected. In certain cases such a thermal power station can even outperform hydroelectric units when it comes to the ability to exercise frequency control. This project has been a research project at the Department of Electric Power Engineering at Chalmers University of Technology, Gothenburg, Sweden, sponsored by the Swedish National grid authority, Svenska Kraftnät, before 1992 by Vattenfall. It has earlier been presented in a licentiate thesis in January 1994 [2] and in a report presented at the MEPS conference, Wroclaw, Poland in September 1996.